The present invention relates generally to a door suspension assembly and, in particular, to a door suspension apparatus for an elevator car door.
The European patent application No. 0 841 286 A1 discloses an elevator car door suspension assembly for opening and closing elevator car doors including a linear induction motor having a pair of movable motor primaries attached to a respective door hanger of each door and a stationary motor secondary attached to a header bracket which is secured to the elevator car, and wherein the motor secondary includes a substantially flat plate which is vertically disposed and is preferably made of a conductive metal such as copper. In this system, in which the door panels are guided by separate rails, a pair of flexible ropes and wheels is needed to keep both panels moving synchronously.
Another known design is a driving apparatus for doors such as is disclosed in U.S. Pat. No. 5,172,518 (Yoshino). This driving apparatus for doors includes a door-like driven body, a conductive rail having an inverted T-shaped configuration serving as a secondary member of a linear motor, two travelling bodies being supported upon a base portion of the conductive rail by means of first rollers, and a primary coil of the linear motor and second rollers disposed upon side surfaces of the unit travelling bodies.
A drawback with the elevator car door suspension assemblies of the known types is instability problems and increased installation and maintenance cost.